Abstract

The induction of acute attacks of bronchospasm by the use of a placebo was investigated in 40 asthmatic subjects. Each patient was told that he would be inhaling 5 different concentrations of some allergen that he had indicated as the cause of his asthma attacks (for example, dust, pollens, animal danders, etc.). In all cases the substance inhaled was physiologic saline. Measurements of airway resistance (Ra) and thoracic gas volume (TGV) were determined by pressure body plethysmography before and after each inhalation. Ra was converted to its reciprocal conductance (Ga) and expressed as a conductance-thoracic gas volume ratio (Ga/TGV). The